Loud speaker



Aug. 9 1927. 1.638,245

C. C. DAVIS LOUD SPEAKER Filed Ju1.v1' 7. 1925 Panarea Aug. 9, 1927.

CHARLES onawroan Davis, Aor rENToN, `iiirciazelusr.

ECE.y

LOUD arianna.

'y Application filed July 17, 192,5.- Serial No. 44,207.

This/'inventionfrelates to devices for the reproduction of sound and more particularly loud speakers such as are used in connection Withvradioreceivers wherein it is desirable that quality of tone-should be preserved to the exclusion of noises or vibrations tending to interfere with the'proper reproduction of sound, and especially is it desirable that such reproducers or loud speakers be free from periods of resonance such as will Iresult in the setting up of sympathetic vibrations in the material of the reproducing medium or diaphragm which will be of an audible degree or frequency and consequently, be the cause of objectionable distortion of or interference, with the required sound reproduction.

AIt is, therefore, the object of this invention to produce a diaphragm construction which will practically eliminate the aforesaid 'ob-v jectionable features hitherto so common in sound amplifyingforms'for loud speakers in a very simple and highly eiiicient manner', the

said invention further aiming to provide a diaphragm wherein vibrations impressed thereon will be truly reproduced, and where in there will be no point of resonance which would set up a sympathetic vibration of high p enough frequency to produce an audible sound, so that the only sounds produced by thediaphragm would be those resulting from the actual vibrations impressed upon the diaphragm.

' The said inventionfurther contemplates the impressing of vibrations on a diaphragm wherein tension as ordinarily provided is avoided, and wherein the vibrations are impressed upon the diaphragm in a direction parallel thereto instead of at right angles to the plane of the diaphragm as has been hitherto the common practice; and a still i further object of the said invention is to provide for the suspending ofy a diaphragm from opposite edges so that it assumes the form of a depending loop or U-shape, upon one (end of which the vibrations to be reproduced are impressed in the direction of of the diaphragm. ,Y

Still furtherobjects subsidiary to orme'- sulting from the aforesaidobjects, or :fromI the construction or operation of the invention as it may be carried into effect, will become apparent as the said invention is' ,o hereinafter further disclosed.

In carryin the said invention into eiect,

I may provi e within a suitable framework the length or housing a suspended needle or rodA adapted vto be vibrated in the direction of its length by means'of a suitable vibration reproducing unit, and one or m.ore diaphra s of fairly stiif paper or similar materia attached at one end to an abutment carried bythe saidv vibratory ro'd, and at the other end to a suitable `support such as the said housing, the

`said diaphragme being of. substantial area and of greaterlength than the distance between their points of attachment to the said support andl to the said abutment, so that sin a direction extending therealong.

Figure l is a sectional elevation/of a loud speaker embodying the said invention-g Figure 21sl a1 sectional elevation ofthe same, the section being taken lat rightanglesv to that-*shown in Figure 1;

lliigure 3 isda plan 011:"J tigsam, plzirt of the v1 ra or ro su or in ro en awa for the graka of el)p y Figure 4 is a detail view of one of the diasphragms detached, and in a ilat condition.

imilar Acharacters of reference findicate similar-parts in the several figures of the drawln l1in icates a box or framework which may have openings 2 and'3 provided at the sides thereof to permit greater `freedom of passage of sound waves for the diaphragms and 4 is a loud speaker unit, the details of which are not described herein, as it is of a ent types of units may be utilized, the par-` ticular form of vunit not being essential to the invention. The said unit has a vibrato member '5 to which is connected a vertical] disposed vvibratory rod for needle 6 which is suspended byV a spring 7 at its 'iupperend from an adjustable member 8 carried by a support 9'which extends from one side of the .framework v1, v10 `being a nut for effect ing the adjustment `of the said member 8. The spring 7 is of course of suchA a nature arity of i ustration; and

ice

that it does not itself have a resonant point tending to producean audible sound when the device is in operation. r

Securely mounted on the rod 6 is an abutment 11 comprising a air of small blocks y of wood or other suita le material, and 12 are diaphragme in the form of triangular pieces of stiff paper or other suitable material capable of vibrating in the desired manner, the smaller ends 13 of these diaphragms being secured to the outer vertical faces of the abutment 11 on opposite sides of the rod 6, and the broad ends 14 of the said diaphragms being secured such as by binding strips 15 and screws 16 to the upper inner margins of the framework 1.

These diaphragme are of substantially greater length than the distance between their points of attachment to the framework 1, and the abutment 11, so that they are bowed or looped' downwardly as a consequence of which the inner ends 13 of the said diaphragms extend upwardly in a direction approaching parallelism with the axis of said rod 6, so that longitudinal vibration of the said rod as a result of the action of the vibratory unit will cause the abutment'll to impress such vibration upon the ends 13 of the diaphragms 12 in a vertical direction, which 1s of course the direc tion of the disposition of such ends of the diaphragms. This is. contrary to the usual method of impressing vibrations upon a diaphragm, the common practice being to im-l press such vibrationslupon-a diaphragm at right angles or at a substantiall angle to its plane. n

In the presentinstance, the inner ends of the diaphragm are exerting to some extent ay downward ull on the abutment 11 in the direction of) the length of the -dia h'ragm at the point of its attachment, so that the vibrations may be said to be impressed upon such diaphragm in such direction and they are transmitted through said 'a hragm from their inner ends and set up vi ratory motions in the diaphragm corresponding thereto without setting up resonant, vibrations of yan audible nature which would otherwise distort'and reduce the quality of the sound reproduced by such diaphragms.

1,ess,24s

The invention is not limited to the number of diaphragms which may be utilized, as it will be obvlous that these may be varied to 4suit requirements or desirability.

The provision for adjustment of the rod 6 is of course optional and may in many cases not be utilized especially where the vibratory unit 4 is of such nature that no such adjustment isrequired, but in many cases the adjustment of the vibratory element 5 is desirable, and it may be effected in the suggested manner.

The hanging nature Vof the diaphragme overcomes the tendency so strongly presentv thereon other than that resulting from their own weight, and it is found that a loud speaker constructed in the manner described will reproduce both high and low notes without distortion4 and with great fidelity.

This invention may be developed within the scope of the following claim without departing from theessential features of the said invention, and it is desired that the specification and drawing be read as merely villustrative and not in a limiting sense, ex-

cept as-necessitated by the vprior art.

What I claim is In a sound reproducing device, a daphragm support, a vibratory member, means resiliently supporting said vibratory member, means for effecting the vibration of said member, and a diaphragm suspended from opposite ends from said support and said vibratory rod.

In testimony whereof I aix my signature.

CHARLES CRAWFORD Davis. 

